Sideloading IPA files allows you to bypass the modern App Store entirely. This lets you:
Automatically re-signs the IPA with a valid enterprise or developer certificate that still works on iOS 9.3.5 (since free Apple IDs now require iOS 10+ for sideloading in some cases). It could also cache old expired certificates and rotate device dates temporarily — a hackish but historically valid method for legacy devices. Ipa Apps Ios 9.3.5